Practical Estimates of the Errors Associated with the Governing Shearography Equation

Fulton, John W.; Namkung, M.; Melvin, Leland D.

doi:10.1007/978-1-4615-2848-7_55

Cited by 8 publications

(6 citation statements)

References 7 publications

(9 reference statements)

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“…For simplicity in discussion, only out of plane surface displacement is considered here (for a more detailed analysis, please see ref. 9). Assuming the displacements at (x, y) and (x-x, y-zy) induced by stress are d(x, y) and d(x-x, y-Ay), then, the speckle image intensity can be written as where I (x, y) = a(x, y)+b(x,y)cos((x,y)+ (x, y)) Ø(x, y) =(d(x, y)-d(x-x, y _iy)).4ii/A where the beat fringe pattern sin(A4(x, y)/2) reflects the distribution of surface displacement gradients.…”

Section: Subtraction Shearographymentioning

confidence: 93%

<title>Real-time portable phase-stepping shearography system for NDE</title>

Bard

1998

SPIE Proceedings

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Shearography has been shown to be a powerful tool for on-site non-destructive evaluation applications, especially in aircraft component inspections. However, current commercially available portable shearography systems are qualitative, low signal to noise ratio, and low flaw detection sensitivity. In this paper, we will introduce a real-time, high-resolution, portable, phase-stepping shearography system developed at the Applied Research Lab of The Pennsylvania State University. The system can fit into a wheeled cart and run at a speed of 1-2 inspections/sec for a 7"x5" field of view. It provides full quantitative analysis ability and substantially improves flaw detection sensitivity. The applicability and portability of the system to on-site field NDE applications have been tested by a successful field demonstration conducted at a naval air station.

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Section: Subtraction Shearographymentioning

confidence: 93%

<title>Real-time portable phase-stepping shearography system for NDE</title>

Bard

1998

SPIE Proceedings

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“…Thus in shearography the gradients are computed using the linearised displacements. Equation linearisation was discussed as a systematic error source in shearography calculations by Fulton et al [19] and by Steinchen et al [20]. The conclusion drawn in these papers was that the errors are negligible, the relative error being less than 1%, except in extreme cases.…”

Section: Errors In Shearographymentioning

confidence: 99%

Calibration and correction procedure for quantitative out-of-plane shearography

Zastavnik

Pyl

et al. 2015

Meas. Sci. Technol.

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Quantitative shearography applications continue to gain practical importance. However, a study of the errors inherent in shearography measurements, related to calibration of the instrument and correction of the results, is most often lacking. This paper proposes a calibration and correction procedure for the out-of-plane shearography with a Michelson interferometer. The calibration is based on the shearography measurement of known rigidbody rotations of a flat plate and accounts for the local variability of the shearing distance. The correction procedure further compensates for the variability of the sensitivity vector and separates the two out-of-plane deformation gradients when they are coupled in the measurement. The correction procedure utilizes two shearography measurements of the same experiment with distinct shearing distances. The effectiveness of the proposed calibration procedure is demonstrated in the case of a static deformation of a centrally loaded plate, where the discrepancy between experimental and finite element analysis results is minimized.

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“…The technique is based on the deformation gradient detection and the inspection time is much shorter in comparison to ultrasonic or mechanical impedance analysis. If we define transformation direction parallel to the x axis, the equation which describes the phase relation may be presented as follows [20]:…”

Section: Detecting Delaminations and Inclusionsmentioning

confidence: 99%

Studying Efficiency of NDE Techniques Applied to Composite Materials in Aerospace Applications

Dragan

Świderski

2010

Acta Phys. Pol. A

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This work presents the modern approach to the detection of various types of defects in composite structures used in aerospace. In such structures, including glass reinforced plastics and carbon reinforced plastics, different failure modes could occur at a manufacturing stage and during service life. Defects are connected with inadequate technology, poor workmanship, cycling fatigue loads, impact damage and environmental conditions. The main types of defects are delaminations, disbonds, foreign object inclusions and porosity. To detect such defects, several non destructive evaluation techniques can be applied, merely to mention ultrasonic, low frequency acoustics, infrared thermography and shearography. The use of multimode non destructive evaluation techniques enables characterization of defects which cannot be detected by using single non destructive evaluation methods. This paper demonstrates the necessity of using non destructive evaluation methods for the implementation of quality control and maintenance procedures while servicing aerospace composite elements.

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Practical Estimates of the Errors Associated with the Governing Shearography Equation

Cited by 8 publications

References 7 publications

<title>Real-time portable phase-stepping shearography system for NDE</title>

<title>Real-time portable phase-stepping shearography system for NDE</title>

Calibration and correction procedure for quantitative out-of-plane shearography

Studying Efficiency of NDE Techniques Applied to Composite Materials in Aerospace Applications

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